1. Field of the Invention
The present invention relates to the technical field of radiation imaging, in particular, relates to an innovative scintillator panel and a radiation image sensor device using the scintillator panel, which is capable of overlapping images of multiple energy levels, to thereby achieve higher resolution and improved recognition of symptoms.
2. Description of the Prior Art
With advances in medical technology, many diseases can get quick and accurate diagnosis through X-ray medical imaging or radioactive scanning techniques, such as chest X-rays, bone X-rays, dental X-rays, X-rays of the breast, or computed tomography (CT), and so on. However, the modern therefore receive a higher radiation dose than in the past. Therefore, the researchers have been striving to reduce the radiation dose absorbed and potential radiation damage without compromising the imaging quality.
Generally, medical X-ray imaging apparatus comprises an X-ray tube and a radiation image sensor. U.S. Patent Publication No. 2004/0211918A1 discloses a radiation imaging apparatus including a scintillator panel and an imaging device. The scintillator panel is composed of an aluminum substrate and thallium-doped cesium iodide (CsI: Tl) layer in columnar crystalline form. Prior to the formation of the CsI: Tl scintillator layer, the surface of the aluminum substrate is coated with a magnesium fluoride (MgF2) layer. To avoid deliquescence of thallium-doped cesium iodide, the aluminum substrate has to be completely encapsulated by using a polymer film.
However, these previous techniques still have many shortcomings. For example, the manufacturing process is complicated and expensive, and thallium used in the manufacturing process is highly toxic. Therefore, sophisticated gas filtration systems are required to avoid environmental pollution. Further, limited by the material properties, thallium is not uniformly doped in the cesium iodide, but can only be doped in a shallow layer, resulting in poor light conversion efficiency. That means a higher energy X-ray exposure is usually needed. Moreover, in order to achieve the desired luminous efficiency, the thickness of the columnar crystalline CsI: Tl has to be 600 microns or more. In addition, due to its hydrolysis characteristics, CsI: Tl is easily influenced by moisture, and therefore storage of CsI: Tl becomes a problem.
Typically, scintillator is composed of a single material. For different X-ray energy levels, only one certain quantum efficiency and only one certain conversion efficiency are obtained. Only the image of certain energy level can be converted from X-ray energy that penetrates through the human body or an object. However, such image data is not adequate to diagnose the lesions. Therefore, radiation imaging with higher doses is required, such as computed tomography or 3D image reconstruction. This results in increased radiation dose, harmful to human health. In light of the above, the industry still needs a novel radiation imaging device and scintillator panels to solve the above shortcomings.